Governments and roadway operating organizations attempt to incentivize carpooling as a mechanism to reduce traffic jams, fuel consumption, and pollution. Having high-occupancy vehicle lanes (HOV lanes, also known as carpooling lanes) exclusive for vehicles carrying a minimum number of people (often 2 or 3) is one of the incentives that can be offered. Another incentive for carpooling is offering discount at tolls for HOV.
U.S. Patent Publication 2008/0175438 discloses a traffic lane enforcement system including a digital camera for providing for a vehicle image and a passenger image of a vehicle passing by in a controlled traffic lane;
WO 2013004864 discloses an automatic control system for vehicles in occupation of a toll station including image acquisition devices, means for removing the effects of glare on the windshield, means for determining the number of occupants in the vehicle, and means for acquiring images comprise at least two cameras, in which each camera acquires at least one image.
U.S. Pat. No. 8,013,760 discloses an electronic toll collection system, reader, and transponder for communicating occupancy status. The vehicle-mounted transponder includes a selection device that permits a user to select between a normal and high occupancy state. The transponder reports its occupancy status to a reader. If the electronic toll collection system processes a toll transaction and the transponder claims high occupancy status during the toll transaction, the fact that high occupancy status was claimed during the transaction is recorded in memory within the transponder for later enforcement and verification purposes.
EP 2275996 discloses providing at least one sensor placed in each of the seats of the vehicle, a controlling unit linked to the sensors for the reception of a signal informing of the presence or absence of a person sitting on the seat, and a data transmission unit for sending the data captured by said sensors upon receiving an order from the external device, in such a way that when the vehicle enters an area, the payment facility of said area, which is adapted for communicating with the transmission unit provided in the vehicle, receives a signal informing it of the number of passengers sitting inside the vehicle and subsequently the payment facility establishes a fee according to the number of passengers.
U.S. Patent Publication 2006/0180377 discloses a single high-frequency transmitter which emits radiation in a vehicle that is reflected depending on whether a seat is occupied, and transmits to a receiver for evaluation with regard to the radiation intensity.
EP 2503514 discloses a system to verify a carpool operation comprising a server, two digital assistants each equipped with a means of acquiring data, including acceleration, position, speed and rotation of the vehicle during a time interval corresponding to a movement of a carrier of the digital assistant and a communication network between the server and the two digital assistants. The server compares geolocation data from both digital assistants for determining a carpool.